logd: initial checkin.

* Create a new userspace log daemon for handling logging messages.

Original-Change-Id: I75267df16359684490121e6c31cca48614d79856
Signed-off-by: Nick Kralevich <nnk@google.com>

* Merge conflicts
* rename new syslog daemon to logd to prevent confusion with bionic syslog
* replace racy getGroups call with KISS call to client->getGid()
* Timestamps are filed at logging source
* insert entries into list in timestamp order
* Added LogTimeEntry tail filtration handling
* Added region locking around LogWriter list
* separate threads for each writer
* /dev/socket/logd* permissions

Signed-off-by: Mark Salyzyn <salyzyn@google.com>

(cherry picked from commit 3e76e0a49760c4970b7cda6153e51026af98e4f3)

Author: Nick Kralevich <nnk@google.com>
Change-Id: Ice88b1412d8f9daa7f9119b2b5aaf684a5e28098
diff --git a/rootdir/init.rc b/rootdir/init.rc
index 46fb8bd..3c52ba9 100644
--- a/rootdir/init.rc
+++ b/rootdir/init.rc
@@ -456,6 +456,12 @@
 on property:ro.kernel.qemu=1
     start adbd
 
+service logd /system/bin/logd
+    class main
+    socket logd stream 0666 logd logd
+    socket logdr seqpacket 0666 logd logd
+    socket logdw dgram 0222 logd logd
+
 service servicemanager /system/bin/servicemanager
     class core
     user system